webpack4 使用babel处理ES6语法的一些简单配置

npm install --save-dev babel-loader @babel/core
npm install @babel/preset-env --save-dev
npm install --save @babel/polyfill
npm install --save-dev @babel/plugin-transform-runtime
npm install --save @babel/runtime

npm install @babel/runtime-corejs2 -D 

module: {
  rules: [
    { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader" }
  ]
}

{
  "plugins": [
    [
      "@babel/plugin-transform-runtime",
      {
        "absoluteRuntime": false,
        "corejs": 2,
        "helpers": true,
        "regenerator": true,
        "useESModules": false
      }
    ]
  ]
}

{ 
    test: /\.js$/, 
    exclude: /node_modules/, 
    loader: "babel-loader",
    options: {
        // "presets": [["@babel/preset-env",{
        //     "targets": {
        //         "chrome": "67"
        //     },
        //     useBuiltIns: "usage",
        // }]]
        "plugins": [
            [
                "@babel/plugin-transform-runtime",
                {
                    "absoluteRuntime": false,
                    "corejs": 2,
                    "helpers": true,
                    "regenerator": true,
                    "useESModules": false
                }
            ]
        ]
    }
}